The present invention relates to a relief device which may be either thermally or pressure actuated to relieve pressure in pressurized containers when a pre-determined temperature or pressure in or around the container is exceeded.
Most vehicles or containers containing a gas or liquid under pressure are equipped with relief valves to prevent catastrophic rupture of the vessels in the case of excessive pressures or temperatures. For example, vehicles using alternative fuels such as compressed natural gas require the presence of one or more fuel cylinders onboard containing such gas under pressure. Federally mandated regulations require that such cylinders be equipped with relief valving mechanism which, in the event of a fire, will allow the gas to escape from the cylinder before reaching an unacceptably high pressure. This reduces the potential for an explosion.
Several approaches have been used to produce acceptable thermally-actuated pressure relief valves. For example, one approach has been to incorporate the fusible plug of an eutectic metal that blocks and seals an outlet passage in the pressure vessel. An example of such an approach is taught in U.S. Pat. Nos. 4,744,382 and 4,744,383. In another approach, a fusible plug of a eutectic material is provided to interfere with movement of a valve member. Upon melting of the plug member, the valve member is released, unsealing a flow path to vent pressurized gases from a pressurized container. An example of such an approach is described in U.S. Pat. No. 5,632,297.
However, these known devices typically require relatively large amounts of eutectic material. Further, the fusible plugs of these devices are typically enclosed in a metal housing, thereby insulating the fusible plug from the surrounding environment, and delaying its desired response.
A pressure relief device comprising a body including an exterior surface, a cavity, an inlet, an outlet, and an aperture, each of the inlet, the outlet, and the aperture opening into the cavity, a temperature sensitive bonding element, and a valve, disposed within the cavity and extending through the aperture, including a sealing member and a cap, the cap being joined to the exterior of the body by the temperature sensitive bonding element, and the sealing member being configured to seal the inlet when the cap is joined to the exterior surface of the body.
A pressure relief device comprising a body including an exterior surface, a cavity, an inlet, an outlet, and an aperture, each of the inlet, the outlet, and the aperture opening into the cavity, and a valve, disposed within the cavity and extending through the aperture, including a sealing member and a temperature sensitive cap, the temperature sensitive cap being joined to the exterior of the body and configured to separate from the body above a predetermined temperature, and the sealing member being configured to seal the inlet when the temperature sensitive cap is joined to the exterior surface of the body.
A pressure relief device comprising a body including a cavity, an inlet, and an outlet, each of the inlet and the outlet opening into the cavity, a first temperature sensitive bonding element, and a valve, disposed within the cavity, including a sealing member, shaft, and a valve bonding element, the shaft including a longitudinal axis and joining the valve bonding element to the sealing member, the valve bonding element extending laterally outwards from the shaft and including a first valve bonding surface presenting a first planar surface, wherein the axis of the shaft is transverse to the first planar surface, and wherein the first valve bonding surface is joined to a first opposing surface of the body by the first temperature sensitive bonding element, wherein the first opposing surface is interposed between the first valve bonding surface and the valve seat, and wherein the sealing member is configured to seal the inlet when the valve is joined to the body.
A pressure relief device comprising a body including an exterior surface, a cavity, an inlet, and an outlet, each of the inlet and the outlet opening into the cavity, a temperature sensitive bonding element, a valve, disposed within the cavity, including a valve retainer and a sealing member, the valve retainer being coupled to the sealing member, the valve retainer being joined to the body by the temperature sensitive bonding element, and the sealing member being biassed into a sealing relationship with the inlet.